Method and apparatus for manufacturing ketene



May'zz, 1945- F. c. ATWOOD 2,376,743

METIiOD AND APPARATUS FOR MANUFACTURING KETENE Filed 001;. 25, 1940 SUPPLY TANK HOLDING TANK CRACKING TUBE DF ALUMINUM COPPER ALLOY PRE-H EATER CQNDENSER *KETENE AND METHANE GAS U SEPARATOR conosnseo ACETONE mQsm-m T+OR Q cracking, but it also withstands very high tem- Patented May 22, 1945 UNITED STATES PATENT, OFFICE METHOD AND APPARATUS FOR MANUFAC- TUR1NG KETENE Francis Clarke Atwood, Newton, Mass., assignorto Atlantic Research'Assoclates, Inc., Newtonville, Mass., a corporation of Delaware Application October as, 1940, Serial No. 362,861

2 Claims. (01. 260-550) This invention relates to a method of and apparatus for manufacturing ketene.

It has been proposed heretofore to prepare ketene from acetone by subjecting acetone vapor to a relatively high temperature in a suitably inert enclosure free from deleterious catalytic agents.

The acetone is "cracked" to yield a mixture of ketene and methane. The enclosing material for the cracking chamber suggested is usually copper. Metals suchas iron, chromium, cobalt and nickel are among the many which are not suitable. It has been proposed, for example, to carryout the cracking operation in a heated copper tube. The recommended temperature was of the order of 675 C. Such a process and apparatus are impractical in a commercial operation because the cracking tube will notstand up under the high temperature and the other conditions incident to the cracking. The failure is due primarily to tion is very low.

I have discovered that a cracking tube or coil formed of an aluminum-copper alloy is admirably suited for the manufacture of ketene. Notonly does this alloy possess the desired properties from the catalytic viewpoint for accomplishing. the

fed to a vaporizer where it is converted into acetone vapor. Steam or any suitable heating means may be used to vaporize the acetone. The acetone vapor, if desired, may be pre-heated by means of a pre-heater which raises the temperature of the vapor, for example, to about 300 to 500 C. From here the vapor is passed into a pyrolysis furnace which consists essentially of a cracking tube or coil formed from an aluminum-copper alloy heated to a cracking temperature. As the acetone vapors pass through this tube, the temperature causes the vapor to be decomposed into ketene and methane. If a pre -heater is not used the vapor is heated in the cracking tube.

The gases exiting from the cracking tube are preferably cooled and any uncracked acetone condensed-and returned to the source of supply. If

desired, any other pyrolysis products are removed by a separator.

The mixture of ketene and methane as are suitable for use in any known process, for exincrease the life of the copper tube, but at lower temperatures the energy efllciency of the operaperatures required to produce an eflicient yield of ketenewithout the deterioration or failure characterized by copper.

It i an object or my invention, therefore, to provide a method and apparatus for preparins ketene utilizing a cracking tube or coil which does not break down the ketene, and which does not deteriorateunder cracking conditions. I

My invention will be better understood from the" following detailed description and from the drawing containing a single figure with self-explanatory legends. In accordance with my invention, the acetone from which the ketene is to be manufactured may be held in suitable supply and holding tanks and ample, the treatment of coagulated and hardened protein filaments for the purpose vof'rendering the latter water resistant; The gas, of course,

. can be used for the ketenization of any liquid or solid material and the latter process is preferably a'continuous one since the supply of ketene is most easily obtained in a continuous operation. Because the methane is inert, it need not be separated from'the ketene prior to the process in which the ketene is utilized, and at the end of the process the methane may be utilized as a source of heat in the pyrolysis furnace, or preferably in the pre-heater.

The pyrolysis furnace may beheated by oil or any other fuel fired means, or it may be heated electrically. It is particularly desirable to make the alloy cracking tube the resistance of an electric circuit whereby the tube itself is heated by the electricity passing through it. The latter method permits the tube tobe completely closed in a ceramic material, thereby completely excluding air from the tube.

The alloy that is preferred is-formedessential- 1y of aluminum and copper, the aluminum being present in the amount of 2 to 10%, preferably near the upper part of this range, for example, 5 to 10%. Practical operation has shown an alloy having about 8% aluminum to be preferred.

The alloy may contain relatively small amounts of other metals which do not have any deleterious action. a

The use of the copper-aluminum alloy permits the employment of much higher temperatures than have been possible heretofore in commercial operations, and in my process I utilize temperatures of the order of 730 to 780 C.,.preferably about 750 to 760 C. without failure of the alloy tube. These temperatures produce much more emcient cracking operations increasing the energy efllciency substantially without lowering the yield obtained by prior art processes utilizing lower temperatures. The high energy efilciency results in a minimum of acetone which much be condensed and recirculated.

The practice of my invention will be apparent from the above description taken in connection with the drawing and may include such variations as will be apparent to one skilled in the art.

I intend all such variations to be within the scope of the invention in the followingclaims.

I claim:

l. A process for the production of ketene which comprises subjecting acetone vapor to a cracking temperature of 700 to 780 C. in contact with an alloy comprising aluminum and copper as its essential constituents and an aluminum content or 2 to 10%.

2. A process for the production of ketene which comprises subjecting acetone vapor to a cracking temperature of 750 to 760 C. in contact with an aluminum-copper alloy having an aluminum content of about 8%.

FRANCIS CLARKE A'I'WOOD. 

